User equipment for satellite communication

ABSTRACT

Disclosed is a user equipment for satellite communication, comprising one or more processing circuits configured to execute the following operations: evaluating a transmission power requirement for a user equipment to communicate with a satellite; and assisting, via an auxiliary device, the user equipment in executing at least part of the communication with the satellite when the transmission power constraint of the user equipment fails to meet the transmission power requirement, wherein the processing circuits are further configured to acquire, via the satellite, a communication mode to be switched to, and the processing circuits transmit, to the satellite, a notification indicating that a current communication mode needs to be switched, with the notification comprising information indicating the need to switch to a communication mode that meets the transmission power requirement.

The present application claims priority to Chinese Patent ApplicationNo. 201810631481.4, titled “USER EQUIPMENT FOR SATELLITE COMMUNICATION”,filed on Jun. 19, 2018 with the Chinese Patent Office, which isincorporated herein by reference in its entirety.

FIELD

The present disclosure relates to satellite communication in a mobilecommunication environment, in particular to a user equipment, asatellite communicating with the user equipment, an assistant device forassisting the user equipment to communicate with the satellite in thesatellite communication, a method of performing satellite communicationin a satellite communication system, and a computer readable storagemedium.

BACKGROUND

Communications satellite is a satellite for transmitting and amplifyingradio communication signals via a transponder, which establishes aninformation channel between a transmission station and a receptionstation on the ground. The communications satellite may be applied infields such as television, telephone, broadcast, network and military.More than two thousand communications satellites run around the orbit ofthe earth, which are used by private and government agencies. In theradio communication, a signal is transmitted with electromagnetic waveswhich travel in straight lines and thus will be blocked by a curvedsurface of the earth. The communications satellite enables long-distancecommunication on the ground by transferring the signal on the surface ofthe earth. The communications satellite uses radio waves and microwavewith a relatively wide frequency band. Since the satellite orbit isquite high above the ground, wave beams of antennas may cover a largearea on the earth. In addition, the propagation of the radio waves isnot limited by terrain, and therefore the long-distance communication onthe ground is possible. In order to make up for the deficiency ofsubmarine cable communication, the communications satellite is usuallyused for mobile communication. For example, a transportation such as aship or a plane which is far away from the land may use thecommunications satellite when the wired communication is not available.Also, the communications satellite may be used for data transmissionwhich has a relatively low requirement of real-time.

The satellite communication mainly refers to radio communication amongrespective earth stations or between the earth station and a spacecraft,in which signals are forwarded via the communications satellite. Thesatellite communication mainly includes satellite relay communication,satellite direct broadcast, satellite mobile communication and satellitefixed communication. The satellite relay communication is wirelesscommunication in which signals are forwarded between the earth stationand the spacecraft via the communications satellite. The satellitedirect broadcast, the satellite mobile communication and the satellitefixed communication are each wireless communication in which signals areforwarded between the respective earth stations via the communicationssatellite. Each of these communications has advantages of largecapacity, wide frequency band, large coverage, distance-independentcost, not being influenced by geological condition, flexibility,reliable and stable performance, wide applicability and the like.However, since the satellite is very far away from the ground, thesatellite communication is applicable to only data transmission with alow requirement of real-time.

SUMMARY

A general summary of the present disclosure is provided here, ratherthan full disclosing of the whole scope or all features of the presentdisclosure.

The present disclosure relates to a user equipment, a satellite, anassistant device, a method and a storage medium in satellitecommunication, which enable data transmission satisfying requirements oftransmission speed or reliability to be performed between the user andthe satellite even if the transmission power constraint of the userequipment fails to satisfy the transmission power demand of thesatellite communication.

According to an aspect of the present disclosure, a user equipmentcapable of performing satellite communication is provided. The userequipment includes one or more processing circuitries. The processingcircuitry is configured to perform the operations of evaluating atransmission power demand of the user equipment to perform communicationwith a satellite, and assisting the user equipment, by an assistantdevice, to perform at least a part of the communication with thesatellite when a transmission power constraint of the user equipmentfails to satisfy the transmission power demand, wherein the processingcircuitry is further configured to acquire, via the satellite, acommunication mode to be switched to, wherein the processing circuitrysends to the satellite a notification indicating a necessity ofswitching a current communication mode, and the notification includesinformation indicating a necessity of switching to a communication modesatisfying the transmission power demand.

According to another aspect of the present disclosure, an assistantdevice for assisting a user equipment to perform communication with asatellite is provided. The assistant device includes a receiverconfigured to receive data which is to be sent to the satellite by theuser equipment via the assistant device, and a transmitter configured tosend the data to the satellite.

According to another aspect of the present disclosure, a method ofperforming satellite communication in a satellite communication systemis provided. The method includes: evaluating, by a user equipment, atransmission power demand for performing communication with a satellite;and triggering switching to a candidate communication mode in which atransmission power constraint of the user equipment satisfies thetransmission power demand, when the transmission power constraint of theuser equipment fails to satisfy the transmission power demand.

According to another aspect of the present disclosure, a computerreadable storage medium is provided. The computer readable storagemedium includes executable computer instructions. The executablecomputer instructions cause a computer to perform the method describedin the present disclosure when being executed by the computer.

With the user equipment, the satellite, the assistant device, the methodand the storage medium according to the present disclosure, datatransmission satisfying requirements of transmission speed orreliability can be performed between the user and the satellite, even ifthe transmission power constraint of the user equipment fails to satisfythe transmission power demand of the satellite.

More applicable fields will become apparent from the descriptionprovided herein. The description and specific examples in the summaryare only schematic, and do not intend to limit the scope of the presentdisclosure.

BRIEF DESCRIPTION OF TILE DRAWINGS

Drawings described herein show only schematic embodiments rather thanall possible embodiments, and are not intended to limit the scope of thepresent disclosure. In the drawings:

FIG. 1A shows a schematic diagram of transmitting of a user terminalwith a decreased transmission speed in order to maintain satellitecommunication;

FIG. 1B shows a schematic diagram of transmitting of a user terminalwith a reduced reliability in order to maintain satellite communication;

FIG. 2A shows a schematic diagram of performing satellite communicationby a user equipment by means of an assistant device according to anembodiment of the present disclosure;

FIG. 2B shows a signaling flowchart of communication between a satelliteand a user equipment according to an embodiment of the presentdisclosure;

FIG. 2C shows a signaling flowchart of communication between asatellite, a user equipment and an assistant device according to anembodiment of the present disclosure;

FIG. 2D shows a signaling flowchart of communication between a satelliteand a user equipment according to an embodiment of the presentdisclosure;

FIG. 3A shows a schematic diagram of accessing to a satellite again by auser equipment after waiting for a delay period according to anembodiment of the present disclosure;

FIG. 3B shows a signaling flowchart of accessing to a satellite again bya user equipment after waiting for a delay period according to anembodiment of the present disclosure;

FIG. 3C shows a signaling flowchart of accessing to a satellite again bya user equipment after waiting for a delay period according to anotherembodiment of the present disclosure;

FIG. 4 shows a signaling flowchart of a random access process accordingto an embodiment of the present disclosure;

FIG. 5 shows a structural block diagram of a user equipment according toan embodiment of the present disclosure;

FIG. 6 shows a structural block diagram of an assistant device accordingto an embodiment of the present disclosure;

FIG. 7 shows a structural block diagram of a satellite according to anembodiment of the present disclosure;

FIG. 8 shows a flowchart of a method for performing satellitecommunication in a satellite communication system according to anembodiment of the present disclosure;

FIG. 9 shows a block diagram of a first example of a schematicconfiguration of an eNB (evolution Node Base station) or gNB (a basestation in a fifth generation of communication system) to which thepresent disclosure is applicable;

FIG. 10 shows a block diagram of a second example of the schematicconfiguration of the eNB or gNB to which the present disclosure isapplicable;

FIG. 11 shows a block diagram of an example of a schematic configurationof a smart phone to which the present disclosure is applicable; and

FIG. 12 shows a block diagram of an example of a schematic configurationof a vehicle navigation device to which the present disclosure isapplicable.

Although the present disclosure is easily subjected to variousmodifications and replacements, specific embodiments as examples areshown in the drawings and described in detail here. However, it shouldbe understood that, the description of specific embodiments is notintended to limit the present disclosure. In contrast, the presentdisclosure is intended to cover all modifications, equivalents andreplacements falling within the spirit and scope of the presentdisclosure. It should be noted that, corresponding reference numeralsindicate corresponding components throughout several drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

Examples of the present disclosure are fully disclosed with reference tothe drawings. The description below is only schematic in essence, and isnot intended to limit the present disclosure, application or usage.

Schematic embodiments are provided, so that the present disclosure willbecome thorough and fully convey the scope thereof to those skilled inthe art. Many specific details such as examples of specific components,devices and methods are clarified here, to provide detailedunderstanding of embodiments of the present disclosure. It is apparentfor those skilled in the art that, the schematic embodiments may beimplemented by many different ways without using specific details, whichshould not be understood as limiting the scope of the presentdisclosure. In some schematic examples, well-known processes, structuresand technologies are not described in detail.

The UE (user equipment) involved in the present disclosure includes butnot limited to a terminal having a wireless communication functionincluding satellite communication, such as a mobile terminal, acomputer, and a vehicle mounted device. Further, depending on specificfunctions described, the UE involved in the present disclosure may be aUE itself or components thereof, for example a chip. In addition, theassistant device involved in the present disclosure is any device havinga satellite communication function, includes but not limited to a basestation, a satellite and other terminal. Similarly, a base stationfunctioning as the assistant device may be, for example, an eNB(evolution Node Base station), a gNB (a base station in the fifthgeneration of communication system), or components of eNB or gNB, suchas a chip.

In the satellite mobile communication system, a satellite is far awayfrom ground, resulting in that the user terminal consumes greater powerin communicating with the satellite than in communicating with theground. A volume of the user terminal is limited, and a transmissionpower of the user terminal is generally limited. Therefore, a case thata calculated transmission power for satellite communication is greaterthan a maximum allowable transmission power of the user terminal mayoccur with a great probability. Even in the above case, it is requiredto ensure that data transmission satisfying a transmission speed orreliability expectation can be performed between the user and thesatellite.

In a case that the transmission power required for satellitecommunication is greater than the maximum allowable transmission powerof the user terminal, generally, a transmission power within acapability range of the current user equipment is selected fortransmission, that is, a transmission power not exceeding the maximumallowable transmission power is selected for transmission. In this case,the user has to reduce the requirement on the transmission speed orreliability, and thus communication with a decreased transmission speedor a reduced transmission reliability can be performed between the userand the satellite.

Therefore, it is required to provide a technical solution, so that datatransmission satisfying a transmission speed or reliability expectationcan be performed between the user and the satellite, even if thetransmission power constraint of the user equipment cannot satisfy thetransmission power demand.

FIG. 1A and FIG. 1B show solutions adopted in the conventionaltechnology when a current data transmission capability of a userequipment cannot satisfy a transmission power demand, so as to maintaincommunication with a satellite by the user terminal,

FIG. 1A shows a schematic diagram of transmitting of a user terminalwith a decreased transmission speed in order to maintain communicationwith a satellite.

The user equipment shown in FIG. 1A expects to communicate with thesatellite at a predetermined fixed data speed. In order to maintain thedata speed, the user equipment is required to have a transmission poweradapting to the data speed. Therefore, the user equipment needs tocalculate a transmission power adapting to continuous transmission ofdata at the data speed. If the current data transmission capability ofthe user equipment cannot satisfy the calculated transmission powerdemand, the required transmission power may be reduced as shown in FIG.1A. As an example, in FIG. 1A, data B which is supposed to betransmitted in one transmission process (lasting for a fixed continuoustime period) is divided into two parts and transmitted in twotransmission processes. Apparently, reduction of the data speedincreases the data transmission time, resulting in bad user experience.Particularly, the solution described above is not applicable to ascenario with a high delay requirement.

FIG. 1B shows a schematic diagram of transmitting a reduced reliabilityby the user terminal in order to maintain satellite communication.

The user equipment shown in FIG. 1B expects to communicate with asatellite to transmit all data to be transmitted. Similar to the caseshown in FIG. 1A, in order to transmit all data to be transmitted, theuser equipment is required to have a transmission power for transmittingall data to be transmitted. Therefore, similarly, the user equipment isrequired to calculate a transmission power required for transmitting alldata to be transmitted. When the current data transmission capability ofthe user equipment cannot satisfy the calculated transmission powerdemand, transmission may be performed with a reduced reliability, asshown in FIG. 1B. As an example, in FIG. 1B, only a part of data B to betransmitted is transmitted. Apparently, loss or discarding of data willinfluence the user experience (although a part of data may be lost incertain applications). Particularly, the solution described above is notapplicable to the application scenario with a high requirement on dataintegrity.

Therefore, in the satellite communication, in a case that the currentdata transmission capability of the user equipment cannot satisfy thetransmission power demand for satellite communication, the existingsatellite communication solution has a lot of disadvantages.

FIG. 2A shows a schematic diagram of performing satellite communicationby a user equipment via an assistant device. As shown in FIG. 2, a set Bof bits to be transmitted is divided into two parts, B1 and B2.Transmission of the bits in the set B2 may be beyond the transmissioncapability range of the user equipment due to power limitation. The userequipment transmits bits in the set B2 to the assistant device shown inthe figure. Then, the user equipment and the assistant devicerespectively transmit the bits in the transmission sets B1 and B2 to thesatellite, and the satellite receives the bits in the sets B1 and B2.Therefore, integrity of data can be guaranteed while ensuring that thecommunication between the user and the satellite meets the expectedtransmission speed. It should be noted that, this process may beunderstood as a switch process based on power. Therefore, it isunnecessary for the user terminal to transmit the bits with an upperlimit of its capability range, and the bits may be configured accordingto demand. For example, it is possible to transmit all bits to thesatellite by the assistant device (that is, the set B1 is empty).

FIG. 2B shows a signaling flowchart of communication between a satelliteand a user equipment according to an embodiment of the presentdisclosure.

In step 1 of FIG. 2B, the user equipment calculates a transmission powerdemand for transmitting data to be transmitted. For those skilled in theart, in a case of capable of obtaining or having obtained relatedparameters of the satellite and the user equipment, the transmissionpower required, i.e., the transmission power demand, for transmittingthe data to be transmitted can be calculated. The detailed process ofcalculating is not described in detail here.

Subsequently, in step 2 of FIG. 2B, the user equipment determineswhether a condition for triggering a candidate communication mode issatisfied according to the transmission power demand calculated in step1. In a case that transmission power constraint of the user equipmentcannot satisfy the transmission power demand, switching is triggered toswitch to a candidate communication mode in which the transmission powerconstraint satisfies the transmission power demand.

According to an embodiment of the present disclosure, the transmissionpower constraint of the user equipment is a preset threshold. In thisembodiment, it is determined whether the required transmission power isexcessive by comparing the required transmission power with the presetthreshold, without considering the transmission capability of the userequipment. Specifically, if P_calculate>Thresh is satisfied, it isdetermined that the required transmission power is excessive. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, and Thresh indicates the presetthreshold.

According to an embodiment of the present disclosure, communicationhysteresis is taken into consideration as a part of the transmissionpower constrain. That is, the transmission power constraint of the userequipment is a sum of the preset threshold and the hysteresis. In theembodiment, it is determined whether the required transmission power isexcessive in consideration of the hysteresis. That is, it is determinedwhether the required transmission power is excessive by comparing therequired transmission power with the sum of the preset threshold and thehysteresis, to avoid a deviation due to the hysteresis. Specifically, ifP_calculate>Thresh+Hys is satisfied, it is determined that the requiredtransmission power is excessive. Then, the user equipment triggersswitching to a candidate communication mode in which the transmissionpower constraint satisfies the transmission power demand. P_calculateherein indicates the required transmission power calculated by the userequipment, Thresh indicates the preset threshold, and Hys indicateshysteresis.

According to an embodiment of the present disclosure, a maximumallowable transmission power of the user equipment is taken intoconsideration as a part of the transmission power constraint. That is,the transmission power constraint of the user equipment is a sum of thepreset threshold and the maximum allowable transmission power of theuser equipment. In this embodiment, it is determined whether therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment in consideration of the maximumallowable transmission power of the user equipment. That is, it isdetermined whether the required transmission power is excessive bycomparing the required transmission power with the sum of the presetthreshold and the maximum allowable transmission power of the userequipment. Specifically, if P_calculate>Thresh+P_may is satisfied, it isdetermined that the required transmission power is much beyond themaximum allowable transmission power of the user equipment. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, Thresh indicates a preset threshold,and P_max indicates a maximum allowable transmission power of the userequipment.

According to another embodiment of the present disclosure, thetransmission power constraint of the user equipment is a sum of themaximum allowable transmission power of the user equipment, thecommunication hysteresis and the preset threshold. Specifically, ifP_calculate>Thresh+P_max+Hys is satisfied, that is, in a case ofconsidering the communication hysteresis, it is determined that therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment. Then, the user equipmenttriggers switching to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates the preset threshold, P_maxindicates the maximum allowable transmission power of the userequipment, and Hys indicates the hysteresis.

Elements included in the transmission power constraint of the userequipment are not limited to the elements described above, any elementwhich may influence the satellite communication or may be taken intoaccount for various requirements, may function as elements of thetransmission power constraint of the user equipment, and the samedetermination is performed as described in the above embodiments. Thatis, in a case that the transmission power constraint of the userequipment cannot satisfy the transmission power demand, switching istriggered to switch to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.

Therefore, in the above embodiments, in a case that the transmissionpower constraint of the user equipment cannot satisfy the transmissionpower demand, the user equipment triggers switching to a candidatecommunication mode in which the transmission power constraint satisfiesthe transmission power demand. In this way, the user equipment canselect the determination manner, and thereby the user equipment cantrigger switching of the communication mode by itself.

In step 3, if it is determined that the triggering condition in step 2is satisfied, the user equipment informs the satellite of thedetermination result. The informing may be performed in one of thefollowing manners: (1) the existing Power Headroom (PH) includes sixhits which can only indicate positive numbers; the number of hits in thePH field remains unchanged, but the six bits are redefined so that theycan indicate negative power; (2) definition of the PH is extended, sothat at least one bit is added for indicating a sign of the carriednumber, and the remaining bits indicate an absolute value of the carriednumber; if the hit for indicating the sign is 0, it is indicated thatthe carried number is a positive number; if the bit for indicating thesign is 1 it is indicated that the carried number is a negative number;it is also possible to define the hit for indicating the sign in areverse way, that is, if the hit for indicating the sign is 1, it isindicated that the carried number is a positive number; if the bit forindicating the sign is 0, it is indicated that the carried number is anegative number; (3) a new field is introduced into a UCI field of thephysical layer, the new field may have only two values, noted as V0 andV1. For example, V0 may be all “0”, and V1 may be all “1”. Otherencoding methods are also possible. If the value of the new field is V0,it is indicated that the calculated transmission power of the user failsto satisfy the triggering condition, and if the value of the new fieldis V1, it is indicated that the calculated transmission power of theuser satisfies the triggering condition.

Next, in step 4, after the satellite receives the report sent by theuser equipment in one of the above manners, the satellite determineswhether it is required to search for an assistant device to assist theuser equipment to transmit data.

In step 5, the satellite informs the user of the determination result.Instead, the satellite provides the determination result to theassistant device such as a base station, and the base station forwardsthe determination result to the user. In step 6, the user equipmentperforms actions according to the received determination result.

FIG. 2C shows a signaling flowchart of communication between asatellite, a user equipment and an assistant device according to anembodiment of the present disclosure.

Compared with FIG. 2B, FIG. 2C further illustrates actions performedaccording to the determination result in step 6 of FIG. 2B. In step 6 ofFIG. 2C, the user equipment selects the assistant device. The satelliteconfigures so that the user searches for an assistant device, or theuser determines an assistant device from a white list. In order to causethe current satellite to determine the white list of the assistantdevices, information such as an orbit, a speed, a capacity and a poweris interacted between adjacent satellites via an interface such as X2,and the information is provided to the user through MIB/SIB/RRC and soon. If the user equipment is configured to search for an assistantdevice by itself, the user equipment searches for the assistant devicefor assisting data transmission according to an algorithm, and allocatesto the assistant device the bits that are beyond the transmissioncapability range of the user equipment due to its power limitation.Then, the user equipment and the assistant device transmit data to thesatellite. Specifically, FIG. 2A shows a flowchart in which threeentities, a satellite, a user terminal and an assistant device areinvolved. First, the user terminal determines an assistant device.Second, the user terminal transmits the bits that are beyond thetransmission capability range (that is, bits in the set B2) to theassistant device. Third, the user terminal transmits the bits within itscapability range or the bits that need to be transmitted by itself (thatis, bits in the set B1) to the satellite, in which case the set B1 maybe empty. Fourth, the assistant device transmits the allocated bits(that is, bits in the set B2) to the satellite.

FIG. 2D shows a signaling flowchart of communication between thesatellite and the user equipment according to another embodiment of thepresent disclosure, as an alternative of the embodiment shown in FIG.2B. Specifically, in step 1 the user equipment calculates acorresponding transmission power for transmitting data. In step 2, theuser equipment checks whether the calculated transmission powersatisfies the triggering condition.

According to another embodiment of the present disclosure, thetransmission power of the user equipment is a preset threshold. In thisembodiment, it may be determined whether the required transmission poweris excessive by comparing the required transmission power with thepreset threshold without considering the transmission capability of theuser equipment. Specifically, if P_calculate>Thresh is satisfied, it isdetermined that the required transmission power is excessive. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, and Thresh indicates a presetthreshold.

According to an embodiment of the present disclosure, communicationhysteresis is taken into consideration as a part of the transmissionpower constraint. That is, the transmission power constraint of the userequipment is a sum of the preset threshold and the hysteresis. In thisembodiment, in a case of considering the hysteresis, it is determinedwhether the required transmission power is excessive. That is, it isdetermined whether the required transmission power is excessive bycomparing the required transmission power with a sum of the presetthreshold and the hysteresis, to avoid a deviation due to hysteresis.Specifically, if P_calculate>Thresh+Hys is satisfied, it is determinedthat the required transmission power is excessive. Then, the userequipment triggers switching to a candidate communication mode in whichthe transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, Thresh indicates the preset threshold,and Hys indicates the hysteresis.

According to an embodiment of the present disclosure, a maximumallowable transmission power of the user equipment is taken intoconsideration as a part of the transmission power constraint. That is,the transmission power constraint of the user equipment is a sum of thepreset threshold and the maximum allowable transmission power of theuser equipment. In this embodiment, it is determined whether therequired transmission power exceeds the maximum allowable transmissionpower of the user equipment. That is, it is determined whether therequired transmission power is excessive by comparing the requiredtransmission power with the sum of the preset threshold and the maximumallowable transmission power of the user equipment. Specifically, ifP_calculate>Thresh+P_max is satisfied, it is determined that therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment. Then, the user equipmenttriggers switching to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates a preset threshold, and P_maxindicates the maximum allowable transmission power of the userequipment.

According to another embodiment of the present disclosure, thetransmission power constraint of the user equipment is a sum of themaximum allowable transmission power of the user equipment, thecommunication hysteresis and the preset threshold. Specifically, ifP_calculate>Thresh+P_max+Hys is satisfied, that is, in a case ofconsidering the communication hysteresis, it is determined that therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment. Then, the user equipmenttriggers switching to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates a preset threshold, P_maxindicates the maximum allowable transmission power of the userequipment, and Hys indicates the hysteresis.

Elements included in the transmission power constraint of the userequipment are not limited to the elements described above, any elementwhich may influence the satellite communication or may be taken intoaccount for various requirements, may function as elements of thetransmission power constraint of the user equipment, and the samedetermination is performed as described in the above embodiments. Thatis, in a case that the transmission power constraint of the userequipment cannot satisfy the transmission power demand, switching istriggered to switch to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.

Therefore, in the above embodiments, in a case that the transmissionpower constraint of the user equipment cannot satisfy the transmissionpower demand, the user equipment triggers switching to a candidatecommunication mode in which the transmission power constraint satisfiesthe transmission power demand.

In step 3, if the triggering condition is satisfied, the user determinesa white list of possible assistant devices, or the satellite configuresthe white list of assistant devices for the user through RRC signaling.Then, the user equipment searches for an assistant device from the whitelist of assistant devices.

In step 4, the user equipment requests the satellite to allocatewireless resources and transmission powers of the satellite for the userequipment and the assistant device.

In step 5, the satellite provides the wireless resources andtransmission powers of the satellite allocated to the user and theassistant device to the user and the assistant device.

In step 6, the user equipment and the assistant device together transmitdata to the satellite according to the resource allocation result.

As described above, FIG. 2A to FIG. 2D show various embodiments in whichthe user equipment maintains communication having the expected speed andreliability with the satellite by means of assisting.

In addition to the manner of transmitting data by means of the assistantdevice, the inventor has recognized that accessing the originalsatellite or another satellite facilitating the communication afterwaiting for a certain delay period is possible.

FIG. 3A shows a schematic diagram of accessing to a satellite again by auser equipment after waiting for a delay period according to anembodiment of the present disclosure.

It is assumed that the user is communicating with the satellite, and thesatellite A transmits a calculated transmission power to the user attime t. In addition, since the satellite A is far away from the user,resulting in that the transmission power demand exceeds the transmissionpower constraint of the user equipment.

Case 1: as shown in (a) of FIG. 3A, the satellite A has not reached theposition above the user at time t. With movement of the satellite, thesatellite A reaches the position above the head of the user at timet+Δt. At this time, the satellite A is nearest to the user, so that thesatellite A can satisfy the requirement of transmission speed andreliability within the transmission power constraint range of the userequipment. Therefore, the satellite A instructs the user to wait fortime Δt, and then the satellite A reconfigures the transmission powerfor the user.

Case 2: as shown in (b) of FIG. 3A, the satellite A has passed theposition above the user at time t. With movement of the satellite, thesatellite A is getting farther and farther away from the user. Whereas,at time t+Δt, a next satellite B reaches the position above the head ofthe user. At this time, the satellite B is nearest to the user, so thatthe satellite B can satisfy the requirements of transmission speed andreliability within the transmission power constraint range of the userequipment. Therefore, the satellite A may instruct the user to wait fortime Δt, and then the satellite B reconfigures the transmission powerfor the user.

FIG. 3B shows a signaling flowchart of accessing to a satellite again bya user equipment after waiting for a delay period according to anembodiment of the present disclosure.

Similar to step 1 in FIG. 2B, in step 1 of FIG. 3B, first, the userequipment calculates a corresponding transmission power demand fortransmitting data to be transmitted.

Next, similar to step 2 in FIG. 2B, in step 2 of FIG. 3B, the userequipment determines whether a condition for triggering a candidatecommunication mode is satisfied according to the transmission powerdemand calculated in step 1. In a case that the transmission powerconstraint of the user equipment cannot satisfy the transmission powerdemand, switching is triggered to switch to a candidate communicationmode in which the transmission power constraint satisfies thetransmission power demand.

According to an embodiment of the present disclosure, the transmissionpower constraint of the user equipment is the preset threshold. In thisembodiment, it is determined whether the required transmission power isexcessive by comparing the required transmission power with the presetthreshold without considering the transmission capability of the userequipment. Specifically, if P_calculate>Thresh is satisfied, it isdetermined that the required transmission power is excessive. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, and Thresh indicates the presetthreshold.

According to an embodiment of the present disclosure, communicationhysteresis is taken into consideration as a part of the transmissionpower constrain. That is, the transmission power constraint of the userequipment is a sum of the preset threshold and the hysteresis. In thisembodiment, it is determined whether the required transmission power isexcessive in consideration of the hysteresis. That is, it is determinedwhether the required transmission power is excessive by comparing therequired transmission power with the sum of the preset threshold and thehysteresis, to avoid a deviation due to the hysteresis. Specifically, ifP_calculate>Thresh+Hys is satisfied, it is determined that the requiredtransmission power is excessive. Then, the user equipment triggersswitching to a candidate communication mode in which the transmissionpower constraint satisfies the transmission power demand. P_calculateherein indicates the required transmission power calculated by the userequipment, Thresh indicates the preset threshold, and Hys indicateshysteresis.

According to an embodiment of the present disclosure, a maximumallowable transmission power of the user equipment is taken intoconsideration as a part of the transmission power constraint. That is,the transmission power constraint of the user equipment is a sum of thepreset threshold and the maximum allowable transmission power of theuser equipment. In this embodiment, it is determined whether therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment in consideration of the maximumallowable transmission power of the user equipment. That is, it isdetermined whether the required transmission power is excessive bycomparing the required transmission power with the sum of the presetthreshold and the maximum allowable transmission power of the userequipment. Specifically, if P_calculate>Thresh+P_max is satisfied, it isdetermined that the required transmission power is much beyond themaximum allowable transmission power of the user equipment. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint meets the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, Thresh indicates a preset threshold,and P_max indicates the maximum allowable transmission power of the userequipment.

According to another embodiment of the present disclosure, thetransmission power constraint of the user equipment is a sum of themaximum allowable transmission power of the user equipment, thecommunication hysteresis and the preset threshold. Specifically, ifP_calculate>Thresh+P_max+Hys is satisfied, that is, in a case ofconsidering the communication hysteresis, it is determined that therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment. Then, the user equipmenttriggers switching to a candidate communication mode in which thetransmission power constraint meets the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates the preset threshold, P_maxindicates the maximum allowable transmission power of the userequipment, and Hys indicates the hysteresis.

Elements included in the transmission power constraint of the userequipment are not limited to the elements described above, any elementwhich may influence the satellite communication or may be taken intoaccount for various requirements, may function as elements of thetransmission power constraint of the user equipment, and the samedetermination is performed as described in the above embodiments. Thatis, in a case that the transmission power constraint of the userequipment cannot satisfy the transmission power demand, switching istriggered to switch to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.

Therefore, in the above embodiments, in a case that the transmissionpower constraint of the user equipment cannot satisfy the transmissionpower demand, the user equipment triggers switching to a candidatecommunication mode in which the transmission power constraint satisfiesthe transmission power demand.

Different from step 3 in FIG. 2B, in step 3 of FIG. 3B, if thetriggering condition is satisfied, the power may be transmitted to thesatellite in one of the following manners: (1) the existing PowerHeadroom (PH) includes six hits which indicate only positive numbers;the number of bits of the PH field remains unchanged, but the six bitsare redefined so that they can indicate negative powers; and (2)definition of the PH is extended, so that at least one bit is added forindicating a sign of the carried number, and the remaining bits indicatean absolute value of the carried number. In one of the above manners,the corresponding negative value of power may be sent to the satellitethrough the extended Power Headroom control element (CE) field of a MAClayer.

In step 4, the satellite determines whether it is necessary for the userto retransmit after waiting for a certain delay period.

The delay period for which the user equipment waits and the white listof satellites based on which the user equipment performs accessing againmay be obtained in the following manner. The current satellite, by usinginformation interacted between adjacent satellites such as an orbit, aspeed, a capacity and a power, calculates the delay period for which theuser equipment waits and the white list of satellites to which the userequipment may access. After calculating the delay period for which theuser equipment waits, the current satellite sends the calculated delayperiod to the user equipment, and provides the white list of satellitesto the user equipment through MIB/SIB/RRC. Alternatively, the satellitemay provide the calculated delay period and the white list of satellitesto the assistant device such as a base station, and then the assistantdevice forwards the delay period and the white list of satellites to theuser. Specifically, the satellite may send the delay period to the userequipment at least in one of the following manners: (1) defining a newMAC layer CE, which means the user performs transmission after waitingfor a period of time, the period is indicated by a combination of bitsin the CE field, and a maximum waiting period that can be indicated isat least a half of a visible period of the satellite; for example, ifthe visible period of the satellite is ten minutes, the maximum waitingperiod of the CF is at least five minutes; and (2) configuring throughRRC signaling. For example, the system may provide a list of possiblewaiting periods to the user through broadcasting, and then the userselects according to its channel condition. If the channel condition isgood, the user selects a short waiting period, and if the channelcondition is poor, the user selects a long waiting period. In step 6, ifit is configured to wait for a delay period, the user waits for thedelay period, and then selects one satellite in the white list toretransmit data. Alternatively, the satellite may be selected by thebase station in the white list, thereby reducing power consumption ofthe user equipment.

FIG. 3C shows a signaling flowchart of accessing the satellite againafter waiting for the delay period by the user equipment according toanother embodiment of the present disclosure. As an alternative of theembodiment shown in FIG. 3B, in step 1, the user equipment calculates acorresponding transmission power for transmitting data.

Next, similar to step 2 in FIG. 2B, in step 2 of FIG. 3C, the userequipment determines whether a condition for triggering the candidatecommunication mode is satisfied according to the transmission powerdemand calculated in step 1. In a case that the transmission powerconstraint of the user equipment cannot satisfy the transmission powerdemand, switching is triggered to switch to a candidate communicationmode in which the transmission power constraint satisfies thetransmission power demand.

According to an embodiment of the present disclosure, the transmissionpower constraint of the user equipment is the preset threshold. In thisembodiment, it is determined whether the required transmission power isexcessive by comparing the required transmission power with the presetthreshold without considering the transmission capability of the userequipment. Specifically, if P_calculate>Thresh is satisfied, it isdetermined that the required transmission power is excessive. Then, theuser equipment triggers switching to a candidate communication mode inwhich the transmission power constraint satisfies the transmission powerdemand. P_calculate herein indicates the required transmission powercalculated by the user equipment, and Thresh indicates the presetthreshold.

According to an embodiment of the present disclosure, communicationhysteresis is taken into consideration as a part of the transmissionpower constrain. That is, the transmission power constraint of the userequipment is a sum of the preset threshold and the hysteresis. In theembodiment, it is determined whether the required transmission power isexcessive in consideration of the hysteresis. That is, it is determinedwhether the required transmission power is excessive by comparing therequired transmission power with the sum of the preset threshold and thehysteresis, to avoid a deviation due to the hysteresis. Specifically, ifP_calculate>Thresh+Hys is satisfied, it is determined that the requiredtransmission power is excessive. Then, the user equipment triggersswitching to a candidate communication mode in which the transmissionpower constraint satisfies the transmission power demand. P_calculateherein indicates the required transmission power calculated by the userequipment, Thresh indicates the preset threshold, and Hys indicateshysteresis.

According to an embodiment of the present disclosure, a maximumallowable transmission power of the user equipment functions is takeninto consideration as a part of the transmission power constraint. Thatis, the transmission power constraint of the user equipment is a sum ofthe preset threshold and the maximum allowable transmission power of theuser equipment. In this embodiment, it is determined whether therequired transmission power is much beyond the maximum allowabletransmission power in consideration of the maximum allowabletransmission power of the user equipment. That is, it is determinedwhether the required transmission power is excessive by comparing therequired transmission power with the sum of the preset threshold and themaximum allowable transmission power of the user equipment.Specifically, if P_calculate>Thresh+P_max is satisfied, it is determinedthat the required transmission power is much beyond the maximumallowable transmission power of the user equipment. Then, the userequipment triggers switching to a candidate communication mode in whichthe transmission power constraint meets the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates a preset threshold, and P_maxindicates a maximum allowable transmission power of the user equipment.

According to another embodiment of the present disclosure, thetransmission power constraint of the user equipment is a sum of themaximum allowable transmission power of the user equipment, thecommunication hysteresis and the preset threshold. Specifically, ifP_calculate>Thresh+P_max+Hys is satisfied, that is, in a case ofconsidering the communication hysteresis, it is determined that therequired transmission power is much beyond the maximum allowabletransmission power of the user equipment. Then, the user equipmenttriggers switching to a candidate communication mode in which thetransmission power constraint meets the transmission power demand.P_calculate herein indicates the required transmission power calculatedby the user equipment, Thresh indicates the preset threshold, P_maxindicates the maximum allowable transmission power of the userequipment, and Hys indicates the hysteresis.

Elements included in the transmission power constraint of the userequipment are not limited to the elements described above, any elementwhich may influence the satellite communication or may be taken intoaccount for various requirements, may function as elements of thetransmission power constraint of the user equipment, and the samedetermination is performed as described in the above embodiments. Thatis, in a case that the transmission power constraint of the userequipment cannot satisfy the transmission power demand, switching istriggered to switch to a candidate communication mode in which thetransmission power constraint satisfies the transmission power demand.

Therefore, in the above embodiments, in a case that the transmissionpower constraint of the user equipment cannot satisfy the transmissionpower demand, the user equipment triggers switching to a candidatecommunication mode in Which the transmission power constraint satisfiesthe transmission power demand.

In step 3, if the triggering condition is satisfied, the user determinesthe delay waiting period and the white list of satellites. In step 4,the user waits for the determined delay period, and then selects onesatellite from the white list of satellites to retransmit data. In thisembodiment, the white list of satellites may be determined and sent tothe user equipment by the satellite. Alternatively, the base station mayselect the satellite from the white list of satellites, thereby reducingpower consumption of the user.

FIG. 4 shows a signaling flowchart of a random access process accordingto an embodiment of the present disclosure.

In this embodiment, during a random access process, if the transmissionpower constraint cannot satisfy the transmission power demand, the userequipment may process according to flows shown in the embodiment.

In step 1, the user equipment calculates a corresponding transmissionpower for transmitting Msg1 in a random access process.

In step 2, the user equipment checks whether the calculated transmissionpower for Msg1 satisfies the triggering condition, if the triggeringcondition is satisfied, the user may determine to access again orreselect one satellite from the white list of satellites for accessing.

In step 3, the user transmits Msg1.

In step 4, the user receives RAR (Random Access Response).

In step 5, the user calculates a corresponding transmission power fortransmitting Msg3.

In step 6, the user checks whether the calculated transmission power forMsg3 satisfies the triggering condition. If the triggering condition issatisfied, the user may determine to access again, or select onesatellite from the white list of satellites for accessing.

In step 7, the user transmits Msg3.

It should be noted that, the triggering condition in the embodiment ofFIG. 4 is the same as the triggering condition in the previousembodiment. The white list of the satellites may be determined by theuser equipment, or may be determined and sent to the user equipment bythe satellite.

According to the various embodiments of the present disclosure, in acase that the transmission power constraint of the user equipment cannotsatisfy the transmission power demand, the user equipment sends a reportof communication failure.

FIG. 5 shows a schematic structural diagram of a user equipmentaccording to an embodiment of the present disclosure. As shown in FIG.5, a user equipment 500 may include a processing circuitry 501. Itshould be noted that, the user equipment 500 may include one or moreprocessing circuitries 501. In addition, the user equipment 500 furtherincludes a communication unit 502 and a storage unit 503. The storageunit 503 is configured to store a white list of assistant devices and/ora white list of satellite devices. In addition, the user equipment 500may include other circuitry.

Further, the processing circuit 501 may include various discretefunctional units to perform different functions and/or operations. Itshould be noted that, the functional units may be physical entities orlogical entities, and units with different names may be implemented bythe same physical entity.

The processing circuit 501 is configured to at least perform one of thefollowing operations: evaluating a transmission power demand of the userequipment to perform communication with a satellite; triggeringswitching to a candidate communication mode in which a transmissionpower constraint satisfies the transmission power demand; obtaining, viathe satellite, a communication mode to be switched to; automaticallydetermining a communication mode to be switched to; selecting anassistant device in a white list of assistant devices; receiving a listof assistant devices; selecting a satellite in a list of satellites foraccess; receiving a delay period from the satellite; generating the listof satellite; receiving the list of satellites from the satellite; andtransmitting a report of communication failure in a case that thetransmission power constraint of the user equipment cannot satisfy thetransmission power demand.

The communication unit 502 is configured to perform all operationsrelated to the communication, such as all communication in the satellitecommunication and all communication between the user equipment and theassistant device. FIG. 6 shows a schematic structural diagram of anassistant device according to an embodiment of the present disclosure.As shown in FIG. 6, an assistant device 600 may include a processingcircuitry 601. It should be noted that, the assistant device 600 mayinclude one or more processing circuitries 601. In addition, theassistant device 600 further includes a communication unit 602. Thecommunication unit 602 is configured to perform all operations relatedto the communication, such as all communication between the assistantdevice and the satellite and all communication between the assistantdevice and the user equipment. In addition, the assistant device 600 mayinclude other circuitry. The communication unit 602 may include areceiver configured to receive data to be sent to the satellite by theuser equipment via the assistant device, and a transmitter configured totransmit data to the satellite.

The processing circuit 601 is configured to at least perform one of thefollowing operations: assisting the user equipment to evaluate atransmission power demand to perform communication with the satellite;assisting the user equipment to obtain data to be transmitted; assistingthe user equipment to receive a white list of satellites; assisting theuser equipment to select a satellite from the white list of satellites;and assisting the user equipment to receive the delay period from thesatellite,

FIG. 7 shows a schematic structural diagram of a satellite according toan embodiment of the present disclosure. As shown in FIG. 7, a satellite700 may include a processing circuitry 701. It should be noted that, thesatellite 700 may include one or more processing circuitries 701. Inaddition, the satellite 700 further includes a communication unit 702.The communication unit 702 is configured to perform all operationsrelated to the communication, such as all communications between thesatellite and the assistant device and all communications between thesatellite and the user equipment. In addition, the satellite 700 mayinclude other circuitry. The communication unit may include a receiverconfigured to receive a notification that the user equipment requests toswitch the current communication mode with the satellite, and atransmitter configured to transmit an instruction on switching to theuser equipment in response to the notification.

The processor 701 is configured to at least perform one of the followingoperations: determining whether the user equipment needs the assistantdevice; determining whether the user equipment is required to retransmitdata after waiting for a delay period; determining whether the userequipment performs random access again; determining a communication modeto which the user equipment intends to switch; configuring, the userequipment to search for the assistant device; generating a white list ofassistant devices; generating a white list of satellites; anddetermining a delay period.

FIG. 8 shows a method for performing satellite communication in asatellite communication system according to an embodiment of the presentdisclosure. In step S801, the user equipment evaluates a transmissionpower demand to perform communication with a satellite. In step S802, itis determined whether a transmission power constraint of the userequipment satisfies a transmission power demand; in a case that thetransmission power constraint of the user equipment satisfies thetransmission power demand, the method proceeds to step S803, andtransmission is performed at a current transmission power; and in a casethat the transmission power constraint of the user equipment cannotsatisfy the transmission power demand, the method proceeds to S804, theuser equipment triggers switching to a communication mode in which thetransmission power constraint satisfies the transmission power demand.

According to the various embodiments of the present disclosure, the userequipment consumes great power in calculating the transmission powerdemand. Therefore, the assistant device such as the base station mayassist the user equipment to calculate values of the transmission powerof an uplink link of the satellite. The assistant device such as thebase station may complete calculation of the transmission power demand,thereby reducing power consumption of the user.

It should be noted that, a computer readable storage medium is furtherprovided according to an embodiment of the present disclosure. Thecomputer readable storage medium includes executable computerinstructions which, when being executed by a computer, cause thecomputer to implement the methods according to the embodiments of thepresent disclosure.

The technology of the present disclosure may be applied to variousproducts. For example, the assistant device described in the presentdisclosure may be a base station. The base station may be implemented asany type of evolved Node B (eNB), such as a macro eNB and a small eNB.The small eNB may be an eNB covering a cell smaller than a macro cell,such as a pica eNB, a micro eNB and a home (femto) eNB. Alternatively,the base station may be implemented as any other type of base station,such as NodeB and a base station transceiver station (BTS). The basestation may include: a body configured to control wireless communication(also referred to as a base station device); and one or more remoteradio head end (RRH) located at a place different from the body. Inaddition, various types of terminal described below may function as abase station by performing functions of the base station temporarily orin a semi-persistent manner.

For example, The UE described in the present disclosure may be a mobileterminal (for example a smartphone, a tablet personal computer (PC), anotebook PC, a portable game terminal, a portable/dangle mobile routerand a digital camera) or a vehicle terminal (such as a vehiclenavigation device). The UE may be implemented as a terminal performingmachine to machine (M2M) communication (also referred to as a machinetype communication (MTC) terminal). In addition, the UE may be awireless communication module (for example an integrated circuit moduleincluding a single chip) installed in each of the above terminals.

FIG. 9 is a block diagram showing a first example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 1000 includes one or more antennas1010 and a base station device 1020. The base station device 1020 andeach of the antennas 1010 may be connected with each other via an RFcable.

Each of the antennas 1010 includes one or more antenna elements (such asmultiple antenna elements included in a multiple-input multiple-output(MIMO) antenna), and is used for sending and receiving a radio signal bythe base station device 1020. The eNB 1000 may include the multipleantennas 1010, as shown in FIG. 9. For example, the multiple antennas1010 may be compatible with multiple frequency bands used by the eNB1000. Although FIG. 9 illustrates an example in which the eNB 1000includes multiple antennas 1010, the eNB 1000 may also include a singleantenna 1010. The base station as the assistant device according to theembodiment of the present disclosure is required to have the capabilityto communicate with the satellite in the air, in addition to thecapability to communicate with the ground user. In this case, inaddition to being provided with the conventional antennas for receivingsignals in the ground direction, the base station as the assistantdevice is also provided with the antenna for receiving signals in theair direction.

The base station device 1020 includes a controller 1021, a memory 1022,a network interface 1023, and a wireless communication interface 1025.

The controller 1021 may be a CPU or a DSP and control various functionsof higher layers of the base station device 1020. For example, thecontroller 1021 generates a data packet based on data in a signalprocessed by the wireless communication interface 1025, and transfersthe generated packet via a network interface 1023. The controller 1021may bundle data from multiple baseband processors to generate bundledpacket, and transfer the generated bundled packet. The controller 1021may have logical functions of performing control such as radio resourcecontrol, radio bearer control, mobility management, admission control,and scheduling. The control may be performed in conjunction with anadjacent eNB or a core network node. The memory 1022 includes RAM andROM, and stores a program that is executed by the controller 1021, andvarious types of control data (such as a terminal list, transmissionpower data, and scheduling data).

The network interface 1023 is a communication interface for connectingthe base station device 1020 to a core network 1024. The controller 1021may communicate with a core network node or another eNB via the networkinterface 1023. In that case, the eNB 1000 and the core network node orthe other eNB may be connected to each other through a logical interface(such as an S1 interface and an X2 interface). The network interface1023 may also be a wired communication interface or a wirelesscommunication interface for radio backhaul. If the network interface1023 is a wireless communication interface, it may use a higherfrequency band for wireless communication than a frequency hand used bythe wireless communication interface 1025.

The wireless communication interface 1025 supports any cellularcommunication scheme (such as Long Term Evolution (LTE) andLTE-Advanced), and provides wireless connection to a terminal positionedin a cell of the eNB 1000 via the antenna 1010. The wirelesscommunication interface 1025 may typically include, for example, a baseband (BB) processor 1026 and an RF circuit 1027. The BB processor 1026may perform, for example, coding/decoding, modulation/demodulation andmultiplexing/de-multiplexing, and perform various types of signalprocesses of the layers (for example Li, media access control (MAC),radio link control (RLC) and packet data convergence protocol (PDCP)).Instead of the controller 1021, the BB processor 1026 may have a part orall of the above-described logical functions. The BB processor 1026 maybe a memory that stores the communication control program, or a modulethat includes a processor and related circuitry configured to performthe program. The function of the BB processor 1026 may be changed whenthe programs are updated. The module may be a card or a blade that isinserted into a slot of the base station device 1020. Alternatively, themodule may be a chip that is mounted on the card or the blade.Meanwhile, the RF circuit 1027 may include, for example, a frequencymixer, a filter and an amplifier, and send and receive a radio signalvia the antenna 1010.

As shown in FIG. 9, the wireless communication interface 1025 mayinclude multiple BB processors 1026. For example, multiple BB processors1026 may be compatible with multiple frequency bands used by the eNB1000. As shown in FIG. 9, the wireless communication interface 1025 mayinclude multiple RF circuits 1027. For example, the multiple RF circuits1027 may be compatible with multiple antenna elements. Although anexample in which the wireless communication interface 1025 includesmultiple BB processors 1026 and multiple RF circuits 1027 is shown inFIG. 9, the wireless communication interface 1025 may also include asingle BB processor 1026 or a single RF circuit 1027.

FIG. 10 is a block diagram showing a second example of a schematicconfiguration of an eNB functioning as a base station to which thetechnology according to the present disclosure may be applied. An eNB1130 includes one or more antennas 1140, a base station device 1150 andan RRH 1160. Each antenna 1140 and the RRH 1160 may be connected to eachother via an RF cable. The base station device 1150 and the RRH 1160 maybe connected to each other via a high-speed line such as a fiber cable.

Each of the antennas 1140 includes one or more antenna elements (such asthe multiple antenna elements included in the AMMO antenna), and is usedfor sending and receiving the radio signal by the RRH 1160. As shown inFIG. 10, the eNB 1130 may include multiple antennas 1140. For example,the multiple antennas 1140 may be compatible with multiple frequencybands used by the eNB 1130. Although an example in which the eNB 1130includes multiple antennas 1140 is shown in FIG. 10, the eNB 1130 mayalso include a single antenna 1140.

The base station device 1150 includes a controller 1151, a memory 1152,a network interface 1153, a wireless communication interface 1155, and aconnection interface 1157. The controller 1151, the memory 1152, and thenetwork interface 1153 are the same as the controller 1021, the memory1022, and the network interface 1023 described with reference to FIG. 9.

The wireless communication interface 1155 supports any cellularcommunication solution (such as LTE and LTE-advanced), and provideswireless communication with a terminal located in a sector correspondingto the RRH 1160 via the RRH 1160 and the antenna 1140. The wirelesscommunication interface 1155 may typically include, for example, a BBprocessor 1156. Other than connecting to an RF circuit 1164 of the RRH1160 via the connection interface 1157, the BB processor 1156 is thesame as the BB processor 1026 described with reference to FIG. 9. Asshow in FIG. 10, the wireless communication interface 1155 may includemultiple BB processors 1156. For example, the multiple BB processors1156 may be compatible with the multiple frequency bands used by the eNB1130. Although FIG. 10 illustrates an example in which the wirelesscommunication interface 1155 includes multiple BB processors 1156, thewireless communication interface 1155 may also include a single BBprocessor 1156.

The connection interface 1157 is an interface for connecting the basestation device 1150 (the wireless communication interface 1155) to theRRH 1160. The connection interface 1157 may also be a communicationmodule for communication in the above-described high-speed line thatconnects the base station device 1150 (the wireless communicationinterface 1155) to the RRH 1160.

The RRH 1160 includes a connection interface 1161 and a wirelesscommunication interface 1163.

The connection interface 1161 is an interface for connecting the RRH1160 (the wireless communication interface 1163) to the base stationdevice 1150. The connection interface 1161 may also be a communicationmodule for the communication in the above high-speed line.

The wireless communication interface 1163 sends and receives a radiosignal via the antenna 1140. The wireless communication interface 1163may generally include, for example, the RE circuit 1164. The RE circuit1164 may include, for example, a frequency mixer, a filter and anamplifier, and send and receive a radio signal via the antenna 1140. Thewireless communication interface 1163 may include multiple RF circuits1164, as shown in FIG. 10. For example, the multiple RE circuits 1164may support multiple antenna elements. Although FIG. 10 illustrates theexample in which the wireless communication interface 1163 includes themultiple RF circuits 1164, the wireless communication interface 1163 mayalso include a single RE circuit 1164.

In the eNB 1000 shown in FIG. 9 and the eNB 1130 shown in FIG. 10, theprocessing circuitry 610 described with reference to FIG. 6 may beimplemented by the controller 1021 and/or the controller 1151, and thecommunication unit 620 described with reference to FIG. 6 may beimplemented by the wireless communication interface 1025 and thewireless communication interface 1155 and/or the wireless communicationinterface 1163. At least a part of the functions may be implemented bythe controller 1021 and the controller 1151. For example, the controller1021 and/or the controller 1151 may perform the control function byexecuting instructions stored in a corresponding memory-.

FIG. 11 is a block diagram showing an example of exemplary configurationof a smartphone 1200 to which the technology of the present disclosuremay be applied. The smart phone 1200 includes a processor 1201, a memory1202, a storage device 1203, an external connection interface 1204, acamera 1206, a sensor 1207, a microphone 1208, an input device 1209, adisplay device 1210, a speaker 1211, a wireless communication interface1212, one or more antenna switches 1215, one or more antennas 1216, abus 1217, a battery 1218 and an auxiliary controller 1219.

The processor 1201 may be, for example, a CPU or a system on chip (SoC),and control functions of an application layer and other layers of thesmart phone 1200. The memory 1202 includes a RAM and a ROM, and stores aprogram that is executed by the processor 1201, and data. The storagedevice 1203 may include a storage medium such as a semiconductor memoryand a hard disk. The external connection interface 1204 is an interfacefor connecting an external device (such as a memory card and a universalserial bus (USB) device) to the smart phone 1200.

The camera 1206 includes an image sensor such as a charge coupled device(CCD) and a complementary metal oxide semiconductor (CMOS), andgenerates a captured image. The sensor 1207 may include a group ofsensors such as a measurement sensor, a gyro sensor, a geomagneticsensor, and an acceleration sensor. The microphone 1208 converts soundsthat are inputted to the smart phone 1200 into audio signals. The inputdevice 1209 includes, for example, a touch sensor configured to detecttouch onto a screen of the display device 1210, a keypad, a keyboard, abutton, or a switch, and receive an operation or information inputtedfrom a user. The display device 1210 includes a screen such as a liquidcrystal display (LCD) and an organic light-emitting diode (OLED)display, and displays an output image of the smart phone 1200. Thespeaker 1211 converts audio signals that are outputted from thesmartphone 1200 to sounds.

The wireless communication interface 1212 supports any cellularcommunication scheme (such as LTE and LTE-Advanced), and performswireless communication. The wireless communication interface 1212 maytypically include, for example, a base band (BB) processor 1213 and a RFcircuit 1214. The BB processor 1213 may perform encoding/decoding,modulating/demodulating and multiplexing/demultiplexing, for example,and perform various types of signal processing for wirelesscommunication. The RF circuit 1214 may include a frequency mixer, afilter and an amplifier for example, and send and receive a radio signalvia the antenna 1216. The wireless communication interface 1212 may be achip module having the BB processor 1213 and the RF circuit 1214integrated thereon. The wireless communication interface 1212 mayinclude multiple BB processors 1213 and multiple RF circuits 1214, asshown in FIG. 11. Although FIG. 11 illustrates the example in which thewireless communication interface 1212 includes the multiple BBprocessors 1213 and the multiple RF circuits 1214, the wirelesscommunication interface 1212 may also include a single BB processor 1213or a single RF circuit 1214.

Moreover, in addition to a cellular communication scheme, the wirelesscommunication interface 1212 may also support a wireless communicationscheme of another type, such as a short-distance wireless communicationscheme, a near field communication scheme, and a wireless local areanetwork (LAN) scheme. In this case, the wireless communication interface1212 may include a BB processor 1213 and an RF circuit 1214 for eachwireless communication scheme.

Each of the antenna switches 1215 switches connection destinations ofthe antennas 1216 among multiple circuits (such as circuits fordifferent wireless communication schemes) included in the wirelesscommunication interface 1212.

Each of the antennas 1216 includes one or more antenna elements (such asmultiple antenna elements included in an MIMO antenna), and is used forthe wireless communication interface 1212 to send and receive radiosignals. The smartphone 1200 may include the multiple antennas 1216, asshown in FIG. 11. Although FIG. 11 illustrates the example in which thesmartphone 1200 includes the multiple antennas 1216, the smartphone 1200may also include a single antenna 1216.

In addition, the smart phone 1200 may include an antenna 1216 for eachwireless communication scheme. In this case, the antenna switches 1215may be omitted from the configuration of the smart phone 1200.

The bus 1217 connects the processor 1201, the memory 1202, the storagedevice 1203, the external connection interface 1204, the camera 1206,the sensor 1207, the microphone 1208, the input device 1209, the displaydevice 1210, the speaker 1211, the wireless communication interface1212, and the auxiliary controller 1219 to each other. The battery 1218supplies power to each block of the smartphone 1200 shown in FIG. 20 viafeeders which are partially shown by dashed lines in the figure. Theauxiliary controller 1219 operates a minimum necessary function of thesmartphone 1200, for example, in a sleep mode.

In the smartphone 1200 shown in FIG. 11, the processing circuitry 510described with reference to FIG. 5 and the obtaining unit 511 and theestimating unit 512 in the processing circuitry 510 may be implementedby the processor 1201 and the auxiliary controller 1219, and thecommunication unit 520 described with reference to FIG. 5 may beimplemented by the wireless communication interface 1212. At least apart of the functions may be implemented by the processor 1201 or theauxiliary controller 1219. For example, the processor 1201 or theauxiliary controller 1219 may perform the information obtaining functionand the estimating function by executing instructions stored in thememory 1202 or the storage device 1203.

FIG. 12 is a block diagram showing an example of a schematicconfiguration of a vehicle navigation device 1320 to which thetechnology according to the present disclosure may be applied. Thevehicle navigation device 1320 includes a processor 1321, a memory 1322,a global positioning system (GPS) module 1324, a sensor 1325, a datainterface 1326, a content player 1327, a storage medium interface 1328,an input device 1329, a display device 1330, a speaker 1331, a wirelesscommunication interface 1333, one or more antenna switches 1336, one ormore antennas 1337, and a battery 1338.

The processor 1321 may be for example the CPU or the SoC, and controlthe navigation function and other functions of the vehicle navigationdevice 1320. The memory 1322 includes a RAM and a ROM, and stores aprogram that is executed by the processor 1321 and data.

The GPS module 1324 determines a position (such as latitude, longitude,and altitude) of the vehicle navigation device 1320 by using GPS signalsreceived from a GPS satellite. The sensor 1325 may include a group ofsensors such as a gyroscope sensor, a geomagnetic sensor and an airpressure sensor. The data interface 1326 is connected to, for example,an in-vehicle network 1341 via a terminal that is not shown, andacquires data generated by the vehicle, such as vehicle speed data.

The content player 1327 reproduces content stored in a storage medium(such as a CD and a DVD) that is inserted into the storage mediuminterface 1328. The input device 1329 includes, for example, a touchsensor configured to detect touch on a screen of the display device1330, a button, or a switch, and receives an operation or informationinputted from a user. The display device 1330 includes a screen such asa LCD or an OLED display, and displays an image of the navigationfunction or content that is reproduced. The speaker 1331 outputs soundsof the navigation function or the content that is reproduced.

The wireless communication interface 1333 supports any cellularcommunication scheme (such as LTE and LTE-advanced) and performswireless communication. The wireless communication interface 1333 maytypically include, for example, a BB processor 1334 and an RF circuit1335. The BB processor 1334 may perform encoding/decoding,modulating/demodulating and multiplexing/demultiplexing, for example,and perform various types of signal processing for wirelesscommunication. The RF circuit 1335 may include a mixer, a filter and anamplifier, for example, and send and receive a radio signal via theantenna 1337. The wireless communication interface 1333 may also be onechip module that has the BB processor 1334 and the RF circuit 1335integrated thereon. The wireless communication interface 1333 mayinclude multiple BB processors 1334 and multiple RF circuits 1335, asshown in FIG. 12. Although FIG. 12 shows the example in which thewireless communication interface 1333 includes the multiple BBprocessors 1334 and the multiple RF circuits 1335, the wirelesscommunication interface 1333 may also include a single BB processor 1334or a single RF circuit 1335.

In addition to the cellular communication scheme, the wirelesscommunication interface 1333 may also support a wireless communicationscheme of another type, such as a short-distance wireless communicationscheme, a near field communication scheme, and a wireless LAN scheme. Inthis case, the wireless communication interface 1333 may include a BBprocessor 1334 and a RF circuit 1335 for each wireless communicationscheme.

Each of the antenna switches 1336 switches connection destinations ofthe antenna 1337 among multiple circuits (such as circuits for differentwireless communication schemes) included in the wireless communicationinterface 1333.

Each of the antennas 1337 includes one or more antenna elements (such asmultiple antenna elements included in the MIMO antenna), and is used forthe wireless communication interface 1333 to send and receive a radiosignal. The vehicle navigation device 1320 may include multiple antennas1337, as shown in FIG. 12. Although FIG. 12 illustrates the example inwhich the vehicle navigation device 1320 includes the multiple antennas1337, the vehicle navigation device 1320 may also include a singleantenna 1337.

Furthermore, the vehicle navigation device 1320 may include the antenna1337 for each wireless communication scheme. In this case, the antennaswitches 1336 may be omitted from the configuration of the vehiclenavigation device 1320.

The battery 1338 supplies power to each block of the vehicle navigationdevice 1320 shown in FIG. 12 via feeders which are partially shown bydashed lines in the figure. The battery 1338 accumulates power suppliedfrom the vehicle.

In the vehicle navigation device 1320 shown in FIG. 12, the processingcircuitry 510 described with reference to FIG. 5, and the communicationunit 520 described with reference to FIG. 5 may be implemented by thewireless communication interface 1033. At least a part of functions maybe implemented by the processor 1321. For example, the processor 1321may perform various functions by executing instructions stored in thememory 1322.

In the system and method of the present disclosure, apparently, variouscomponents or steps may be decomposed and/or recombined. Thedecomposition and/or recombination should be regarded as equivalentsolution of the present disclosure. In addition, steps for performingthe above series of processing may be performed naturally in a timeorder according to the description order, but the steps are unnecessaryto be performed in the time order. Some steps may be performed inparallel or independently.

The embodiments of the present disclosure are described in detail inconjunction with the drawings above. However, it should be understoodthat the embodiments described above are intended to illustrate thepresent disclosure rather than limit the present disclosure. Thoseskilled in the art may make various changes and modifications to theembodiments without departing from the essence and scope of the presentdisclosure. Therefore, the scope of the present disclosure is defined bythe attached claims and equivalents thereof.

1. A user equipment capable of performing satellite communication,comprising: one or more processing circuitries configured to perform theoperations of: evaluating a transmission power demand of the userequipment to perform communication with a satellite; and assisting theuser equipment, by an assistant device, to perform at least a part ofthe communication with the satellite when a transmission powerconstraint of the user equipment fails to satisfy the transmission powerdemand, wherein the processing circuitry is further configured toacquire, via the satellite, a communication mode to be switched to,wherein the processing circuitry sends to the satellite a notificationindicating a necessity of switching a current communication mode, andthe notification comprises information indicating a necessity ofswitching to a communication mode satisfying the transmission powerdemand.
 2. The user equipment according to claim 1, wherein theprocessing circuitry is further configured such that the user equipmentdetermines the communication mode to be switched to, according to aresult of evaluating the transmission power demand.
 3. The userequipment according to claim 1, wherein the notification is sent via PHfield or extended PH field or UCI field.
 4. The user equipment accordingto claim 1, wherein the processing circuitry is further configured toselect the assistant device in a white list of assistant devices,wherein the processing circuitry determines the white list of assistantdevices or acquires the list of assistant devices via the satellite, andwherein the satellite generates and sends the list of assistant devicesto the user equipment in the case of acquiring the list of assistantdevices via the satellite.
 5. The user equipment according to claim 1,wherein the processing circuitry executes for a delay period, andselects a satellite for access in a list of satellites upon completionof the execution, wherein the processing circuitry calculates the delayperiod or acquires the delay period via the satellite, and wherein theprocessing circuitry receives the delay period from the satellite in thecase of acquiring the delay period via the satellite.
 6. The userequipment according to claim 5, wherein the processing circuitry waitsfor the delay period from a moment when the satellite transmitscalculated transmission power to the user equipment, and selects, afterthe delay period, a satellite closest to the user equipment for accessin the list of satellites.
 7. The user equipment according to claim 5,wherein the processing circuitry is further configured to receive thedelay period via CE field or RRC.
 8. The user equipment according toclaim 5, wherein the processing circuitry is further configured to:generate the list of satellites; or acquire the list of satellites fromthe satellite.
 9. The user equipment according to claim 1, wherein in acase where the communication with the satellite is established throughrandom access, the random access is performed again, or a satellite isselected for access from a list of satellites.
 10. The user equipmentaccording to claim 9, wherein the random access is msg1 random access ormsg3 random access.
 11. The user equipment according to claim 1, whereinthe processing circuitry is further configured to receive transmissionobject information via MIB, SIB or RRC, and the transmission objectinformation comprises a list of satellites and a list of assistantdevices.
 12. The user equipment according to claim 1, wherein theprocessing circuitry is further configured to send a report ofcommunication failure when the transmission power constraint of the userequipment fails to satisfy the transmission power demand.
 13. The userequipment according to claim 1, wherein the transmission power demand isa transmission power required by the user equipment to perform thecommunication with the satellite, and wherein the transmission powerconstraint comprises one of: a predetermined threshold; a sum of amaximum allowable transmission power of the user equipment and thepredetermined threshold; a sum of communication hysteresis and thepredetermined threshold; and a sum of the maximum allowable transmissionpower of the user equipment, the communication hysteresis and thepredetermined threshold.
 14. The user equipment according to claim 13,wherein the transmission power constraint of the user equipment fails tosatisfy the transmission power demand in one of the following cases: thetransmission power demand is greater than the predetermined threshold;the transmission power demand is greater than the sum of thecommunication hysteresis and the predetermined threshold; thetransmission power demand is greater than the sum of the maximumallowable transmission power of the user equipment and the predeterminedthreshold; and the transmission power demand is greater than the sum ofthe maximum allowable transmission power of the user equipment, thecommunication hysteresis and the predetermined threshold.
 15. Asatellite for communicating with a user equipment, comprising: areceiver configured to receive a notification that the user equipmentrequests to switch a current communication mode with the satellite; anda transmitter configured to send an instruction on switching to the userequipment in response to the notification.
 16. (canceled)
 17. Thesatellite according to claim 15, wherein the notification comprisesinformation indicating a necessity of switching to a communication modesatisfying the transmission power demand.
 18. The satellite according toclaim 15, wherein the instruction comprises at least one of: a list ofassistant devices; a list of satellites; a notification whether the userequipment needs to use the assistant device; a notification whether theuser equipment needs to wait for a delay period, and/or a length of thedelay period; and a notification whether the user equipment needs toperform random access again.
 19. The satellite according to claim 15,wherein the transmitter is further configured to send resourceallocation information for the communication to the user equipment andthe assistant device.
 20. The satellite according to claim 15, whereinthe receiver is further configured to receive data from the userequipment and/or the assistant device. 21.-22. (canceled)
 23. A methodof performing satellite communication in a satellite communicationsystem, comprising: evaluating, by a user equipment, a transmissionpower demand for performing communication with a satellite; andtriggering switching to a candidate communication mode in which atransmission power constraint of the user equipment satisfies thetransmission power demand, when the transmission power constraint of theuser equipment fails to satisfy the transmission power demand. 24.(canceled)